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Congrats, Vince! Nice looking build you have there- I even recognize those sink. I have a pair or two of them laying around the house waiting for my next build. These are great amps for sure. Three big ones still power my basement theater.
Glad to hear that my web page was a useful reference. I didn't think there was much interest in this "old" design anymore
Did you mount Q6 on the PCB or on the sink? With a single sink, I suppose it is easier and just as effective to put it on the PCB.
Glad to hear that my web page was a useful reference. I didn't think there was much interest in this "old" design anymore
Did you mount Q6 on the PCB or on the sink? With a single sink, I suppose it is easier and just as effective to put it on the PCB.
With this board the output mosfets need to be mounted off the board, creating a bit of a nest of wires. Going to try to zip tie some wire where I can. I missed the bit about Q6 mounting on heat sink.
I didn't match the output mosfets. Just used irfp044 shipped in a tube of 25 count. Still managed to get 16mV and 20mV offset. I can barely hear anything with ear in the speaker.
I was worried the heat sinks wouldn't be large enough but they are. Used. 33 for R5 and R40 and their counterparts. It's set to .525v bias for now, still less bias than when using .22 source resistors.
I'm planning a meter for the front panel. We'll see if I can pull it off. Once I soak in the sound of this one, I'll try to find literature for making upgrades to it. I know they're out there.
Also have AX boards with jfet front end. Oh boy...
Is the jfet front end comparable to the .5?
Thanks all !!!!!
I didn't match the output mosfets. Just used irfp044 shipped in a tube of 25 count. Still managed to get 16mV and 20mV offset. I can barely hear anything with ear in the speaker.
I was worried the heat sinks wouldn't be large enough but they are. Used. 33 for R5 and R40 and their counterparts. It's set to .525v bias for now, still less bias than when using .22 source resistors.
I'm planning a meter for the front panel. We'll see if I can pull it off. Once I soak in the sound of this one, I'll try to find literature for making upgrades to it. I know they're out there.
Also have AX boards with jfet front end. Oh boy...
Is the jfet front end comparable to the .5?
Thanks all !!!!!
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Impressive offset results from not using matched mosfets. I have slowly been using those 044s that I purchased along with boards all of those years ago. Having used higher rail voltage, I went with matched 240 devices. Many of my 044 mosfets have ended up in either various ACA builds or in power regulators.
With non-paralleled output mosfets, you can probably just drop a single pair of J74s in place of the 9610 devices. Might need to tweak a resistor value or two...
With non-paralleled output mosfets, you can probably just drop a single pair of J74s in place of the 9610 devices. Might need to tweak a resistor value or two...
I'm using a modern set of irfp044. Read somewhere that they are not exactly same as original 044s. Don't know... After a few hours I'm getting a fat, round, relaxed sound with a deep sound stage that starts behind the speaker. I guess they can't be all that bad.
My mini-a uses original 044s. Sound is similar but this AX is 3x more powerful and it shows.
My mini-a uses original 044s. Sound is similar but this AX is 3x more powerful and it shows.
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What kind of protection for the meter do you have in mind? If this is a 1v movement (full scale deflection), I don't see that you need to use a diode or fuse for protection. If you wire the meter across the source resistors, you should be at just about half of full scale deflection. If the meter is more sensitive (full scale deflection with much less than one volt), you can probably get away with a dropping resistor. A typical DPDT switch should do it for going back and forth between channels.
Am I missing some other detail?
Am I missing some other detail?
Pass DIY Addict
Joined 2000
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Pass DIY Addict
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For your meter scale, you can use some "water slide" decals that can be printed on your printer. Water Slide decals are clear and come as specific to ink jet or laser printers. Paint the background of your meter whatever color (white, metallic, etc) and put a water slide decal on top, then finish it off with a few coats of clear paint and it will look great.
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Thanks!
I was thinking about it. Family shrunk a little on Monday.
Gave away the ACA and BOZ-J to a friend who exhibited interest in "sitting between his speakers and just listening to music". How could I Pass up the chance to corrupt the poor guy. He'd been using a 90's Sony reciever and Bose speaker. I had straighten him out or else what kind of friend would I be?
As for the pic, it would still be a good turnout to the Summer Reunion. I've got one more amp and preamp cooking!
Thanks.
I was thinking about it. Family shrunk a little on Monday.
Gave away the ACA and BOZ-J to a friend who exhibited interest in "sitting between his speakers and just listening to music". How could I Pass up the chance to corrupt the poor guy. He'd been using a 90's Sony reciever and Bose speaker. I had straighten him out or else what kind of friend would I be?
As for the pic, it would still be a good turnout to the Summer Reunion.
I've got one more amp and preamp cooking!Thanks.
Thanks. The chassis below is a F5 Turbo v2, 50W version. It will go up for sale if anyone wants it. 5U case and dual mono build.
I have two blank Aleph-X board which are ear-marked for a friend, but if he doesn't want them, I will put them up here for free.
What's really interesting about this amp is the ability to sound great with complex, dynamic recordings like orchestras and rock.
I have a tape transfer to digital an orchestra playing folkish music that's just fantastic. Not really my kind of music but it's presented so well that I;m amazed by the instruments themselves.
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